Cap for a writing drawing or painting instrument

ABSTRACT

A cap for a writing, drawing or painting implement, with a cap sheath and a clamping ring, characterised by the fact that the clamping ring is disposed separately in the cap sheath, and the inner peripheral surface the cap sheath and the outer and inner peripheral surfaces of the clamping ring are designed such that, by placing the cap on the housing of a writing, drawing or painting implement and then executing a relative axial twist between the cap and the housing, a firm axial fit between the cap and the housing results.

This patent is the U.S. National Phase of International Application No.PCT/DE02/02445, which was filed on Jul. 4, 2002.

The present invention relates to a cap for a writing, drawing orpainting implement with a cap sheath and a clamping ring.

Many writing implements with removable caps, especially fountain pens,possess a screw-on cap which, while ensuring a secure connection betweenthe housing of the writing implement and the cap, is neverthelessinconvenient and therefore cannot be used quickly.

DE-U 1 802 121 discloses a cap with a clamping ring disposed on thehousing of the writing implement that provides a snap connection. Thereis, however, a risk that the snap connection might give way and that thehousing might slip out of the cap or that the cap might slip out of thehousing.

The invention is therefore based on the problem of improving the genericcap in such a way that a secure connection is provided between thehousing of a writing, drawing or painting implement and the cap, whileat the same time ensuring ease of operation.

In accordance with the invention, this problem is solved by having theclamping ring disposed separately in the cap sheath and designing theinner peripheral surface of the cap sheath and the outer and innerperipheral surfaces of the clamping ring such that, by placing the capon the housing of a writing, drawing or painting implement and thenexecuting a relative axial twist between the cap and the housing, a firmaxial fit between the cap and the housing results.

In particular, it can be provided for the inner peripheral surface ofthe clamping ring to be designed such that, by placing the cap on thehousing, a friction fit or positive fit results between the clampingring and the housing.

In addition, it can be provided for the inner peripheral surface of thecap sheath and the outer peripheral surface of the clamping ring to bedesigned such that, by placing the cap on the housing of the writing,drawing or painting implement and then executing a relative axial twistbetween the cap and the housing, a friction fit results between the capsheath and the clamping ring.

A particular embodiment of the invention is characterised by the factthat at least one wedge-shaped surface rising radially in thecircumferential direction is disposed on the outer peripheral surface ofthe clamping ring and that a corresponding number of matchingwedge-shaped surfaces are disposed on the inner peripheral surface ofthe cap sheath.

It is advantageous for the slopes of the wedge-shaped surfaces facingeach other after the clamping ring has been inserted into the cap sheathto be identical.

Finally, it can be provided for the cap to be designed such that it canbe placed on the housing and creates a seal in the process.

The invention is based on the surprising finding that the use of aclamping ring which develops its function by twisting the cap makes itpossible to create a secure connection in a simple manner. The cap canbe placed on in the usual manner and locked in place with a simple twist(<120°). The use of a separate clamping ring means that it is notnecessary to search radially for the correct position, as is the casewith a bayonet catch.

Furthermore, during the production of the cap, no spindle removal isneeded, which would be necessary with a thread for a screw connection.

Further features and advantages of the invention will become apparentfrom the claims and the following description, in which one workingembodiment is explained in detail with reference to the schematicdrawings. There,

FIG. 1 shows a longitudinal section view of a cap sheath of a cap inaccordance with a particular embodiment of the invention;

FIG. 2 shows a section view along the line II—II in FIG. 1;

FIG. 3 shows a view of the side wall of a housing for a writingimplement;

FIG. 4 shows a perspective view of a clamping ring for the cap;

FIG. 5 shows a view of the clamping ring in the direction of arrow A inFIG. 4;

FIG. 6 shows a view of the clamping ring in the direction of arrow B inFIG. 4;

FIG. 7 shows a section view along the line VII—VII in FIG. 6;

FIG. 8 shows a longitudinal section view of the housing of FIG. 3 withthe cap attached;

FIG. 9 shows a further longitudinal section view of the housing of FIG.3 with the cap attached; and

FIG. 10 shows a section view along the line X—X in FIG. 8.

The cap sheath 10 shown in FIG. 1 has an open end 12 and a closed end(not shown). Beginning at the open end 12, the cap sheath has a firstportion 14 with an internal diameter d₁, a second portion with threewedge-shaped surfaces rising radially in the circumferential direction,only two of which, namely 18 and 20, are visible, a third portion 23with an internal diameter d₂, where d₂<d₁, a fourth portion 24 with aninternal diameter d₃, where d₃<d₂, and a fifth portion 26 with aninternal diameter d₄, where d₄<d₃. This creates inwardly projectingshoulders 28 and 30. Shoulder 30 serves as a stop face for a clampingring (not shown).

As FIG. 2 shows, the wedge-shaped surfaces 18, 20 and 22 each extendthrough 120°.

The housing 32 of a writing implement shown in FIG. 3, e.g. a fountainpen, has a housing tip 34 with two cylindrical portions 36 and 38 withdifferent external diameters, which are connected to one another via afrustoconical portion 40 and the shoulder 39.

FIG. 4 shows a perspective view of a clamping ring 42. It can be clearlyseen that, in its longitudinal direction, the clamping ring 42 haswedge-shaped surfaces 44, 46 and 48 on the outer peripheral surface 3rising radially over a portion in the circumferential direction, whichare shaped in accordance with the wedge-shaped surfaces 18, 20 and 22.Between the wedge-shaped surfaces 44, 46 and 48 in each case, there is agap 50, 52 or 54.

The clamping ring 42 can be subdivided into three portions 56, 58 and60. The wedge-shaped surfaces 44, 46, 48 are disposed in portion 56.Three shoulders 62, 64 and 66 (see also FIG. 6) extending in thecircumferential direction merely over a partial portion are provided inportion 58. The third portion 60 has a constant external diameter, whichis less than the effective external diameter of portions 56 and 58.

FIG. 5 shows a view of the clamping ring 42 in the direction of thearrow A. Each gap 50, 52 and 54 extends over an angular range of 10°.

FIG. 7 shows a section view along the line VII—VII of FIG. 6.

FIG. 8 shows a longitudinal section view of the housing 32 of FIG. 3with the cap 68 attached. The section corresponds to the section of FIG.7. The cap 68 comprises the cap sheath 10 and the clamping ring 42,which is separate from the cap sheath. The clamping ring 42 is infriction fit with the housing 32. In addition, it can be seen that theshoulder 39 of the housing 32 abuts a shoulder 70 on the inside of theclamping ring 42. The clamping ring 42, for its part, has a portion 60which abuts the shoulder 30 (see FIG. 1) of the cap sheath 10.

FIG. 9 shows a further longitudinal section view of the housing 32 ofFIG. 3 with the cap 68 attached. Whereas the section shown in FIG. 8runs through the shoulder 64, this section passes through one of thegaps 50, 52 and 54.

FIG. 10 shows a section view along the line X—X of FIG. 8. The threewedge-shaped surfaces 18, 20 and 22 of the clamping ring 42 and thecorresponding wedge-shaped surfaces 44, 46 and 48 of the cap sheath 10can be seen clearly. When the clamping ring 42 is twisted relative tothe cap sheath 10, its internal diameter is reduced accordingly. Thisleads to the cap 68 being clamped and thus also being firmly seatedaxially on the housing 32. The twisting imparted to the clamping ring 42is caused by the friction fit with the housing 32. The cap 68 can beplaced on in the usual fashion and locked in place with only a slighttwist (<120°).

The features of the invention disclosed in the above description and inthe claims can be essential, both alone and in any combination, forcarrying out the invention in its various embodiments.

1. A cap for a writing, drawing or painting implement comprising; a capsheath having an inner peripheral surface; a clamping ring disposedseparately in the can sheath and having; at least one wedge-shapedsurface that rises radially in a circumferential direction disposed onthe outer peripheral surface of the clamping ring; and a correspondingnumber of respective matching wedge-shaped surfaces disposed on theinner peripheral surface of the cap sheath, wherein the inner peripheralsurface of the clamping ring is designed such that, by placing the capon the housing, a friction fit or positive fit results between theclamping ring and the housing, and wherein the inner peripheral surfaceof the cap sheath and the outer peripheral surface of the clamping ringare designed such that, by placing the cap on the housing and thenexecuting a relative axial twist between the can and the housing, afriction fit results between the cap sheath and the clamping ring,resulting in a firm axial fit between the cap and the housing.
 2. Thecap as claimed in claim 1, wherein slopes of the wedge-shaped surfacesand the matching wedge shaped surfaces facing each other are identicalafter the clamping ring has been inserted into the cap sheath.
 3. Thecap as claimed in claim 1, wherein the cap is designed such that itcreates a seal when placed on the housing.
 4. A cap for a writing,drawing or painting implement, the cap comprising: a cap sheath havingan inner peripheral surface with at least one cap surface portion thatvaries radially in a circumferential direction; a clamping ring disposedgenerally concentrically within the cap sheath, the clamping ring havingan inner peripheral surface and an outer peripheral surface, the outerperipheral surface having at least one ring surface portion that variesradially in a circumferential direction and that can at least partiallyoverlie the at least one cap surface portion, wherein the cap sheath andthe clamping ring can be twisted relative to one another between alocked position in which the inner peripheral surface of the clampingring creates a firm axial fit between the cap and a housing of awriting, drawing or painting implement, and an unlocked position.
 5. Thecap as claimed in claim 4, wherein the inner peripheral surface of theclamping ring creates a positive friction fit between the clamping ringand a housing of a writing, drawing, or painting implement when in thelocked position.
 6. The cap as claimed in claim 4, wherein the at leastone cap surface portion and the at least one ring surface portion createa positive friction fit therebetween when in the locked position.
 7. Thecap as claimed in claim 4, wherein the at least one ring surface portionfurther includes a plurality of wedge-shaped surfaces disposedcircumferentially around the outer peripheral surface of the clampingring, each rising radially in a circumferential direction, and whereinthe at least one cap surface portion further includes a correspondingnumber of matching wedge-shaped surfaces disposed circumferentiallyaround the inner peripheral surface of the cap sheath, each risingradially in a circumferential direction.
 8. The cap as claimed in claim7, wherein each of the wedge-shaped surfaces and its respective matchingwedge-shaped surface has an identical slope.
 9. The cap as claimed inclaim 4, wherein the firm axial fit creates a seal between the clampingring and both the housing and the cap sheath in the locked position.